I don't interface it with the OS, although thats not tough with apple script.
I'm just duplicating the functionality of a fingerworks pad so far. the bandpass filter is coming soon so I can shine light at it.
as for software. max msp is all you need. as for os, Macs are not multimouse-able. I just wrote a protools controller in max.
aside from that, I've been working on a way to traverse the hard drive which utilizes a 3d interface (actually functional, not just showy jurrasic park style)
so they might go together.
pleanty of info on the web. jeff han's paper is 10 bucks